Olanzapine: Palliative Medicine Update

Olanzapine is an atypical antipsychotic agent of the thienobenzodiazepine class. Olanzapine blocks multiple neurotransmitter receptors, including dopaminergic (D1, D2, D3, and D4), serotonergic (5-hydroxytryptamine 2A [5-HT2A], 5-HT2C, 5-HT3, and 5-HT6), adrenergic (α1), histaminic (H1), and muscarinic (M1, M2, M3, and M4) receptors. Olanzapine has a high affinity for the 5HT_2A receptor, which is up to 5 times greater than the dopamine receptor, resulting in less propensity to the development of extrapyramidal side effects. The affinity of olanzapine for multiple receptors has lead to the identification of olanzapine as an important agent in the treatment of delirium, nausea, and vomiting. Olanzapine has been demonstrated to have opioid-sparing properties. Olanzapine is principally metabolized by glucuronidation, with a smaller metabolic contribution from the cytochrome oxidase system. Adverse effects of olanzapine include somnolence, postural hypotension, constipation, dizziness, restlessness, and weight gain. The purpose of this article is to outline the pharmacodynamics, pharmacology, and evidence for the use of olanzapine in palliative care.